Advanced characterization of rubber compounds based on a novel unified physical framework for different experimental approaches

Elasticity in rubber materials depends on different molecular parameters that define the network structure. Crosslinks and entanglements have an effect that is already considered in different ways in the diverse rubber elasticity theories. Different experimental approaches to characterize those parameters are mechanical tests, swelling experiments and more recently double quantum nuclear magnetic resonance (1H DQ-NMR). The analysis of those experiments is based on different assumptions and theoretical approaches, reducing the consistence of the so-obtained results. The main purpose of this work is to unify for the first time those approaches in order to work under just one physical framework as independent as possible from the experiments. This will lead us to a new methodology for the analysis that allows to combine those experimental techniques for a better quantification of structural parameters as crosslink and entanglement density. Moreover, it could set the effect of other important parameters as network defects (dangling chain ends and loops) and spatial distribution of crosslinks (not considered in the rubber elasticity theories) in the physical properties of rubber materials. Finally, the new methodology could be used to characterize filled compounds. These technological relevant products are a complex challenge for quantifying the key-parameters that define their structure. In this sense, there are some effects that are not able to be independently quantified by using a unique experimental approach, such as the matrix overstrain or filler-rubber interactions. The knowledge of those effects and the quantification of them attending to a physical model based on statistical mechanics will provide more accurate molecular parameters that define the network rubber structure in technological relevant rubber compounds